1. Field of the Invention
The present invention relates to a process for producing an inorganic particulate material in the form of fine balls of uniform size, and more particularly to a process for producing such inorganic particulate material utilizing a solution reaction.
The inorganic particulate material obtained by the process of the invention comprises porous or nonporous fine balls which are uniform in size. Since the present material is substantially uniform in particle size, it is usable as a sustained-release inorganic microcapsule film material for enclosing perfumes, dyes, disinfectants, insecticides, repellents for insects and animals, vitamins, foods, nutrients, medicinals, deodorants, adhesives, liquid crystals, etc. in a wide variety of applications.
The present material is useful also as an extender pigment, for example, in the fields of cosmetics, coating compositions, plastics, inks, and agents for preventing adhesion of films.
Moreover, pigments, dyes or like coloring substances can be enclosed with the present material to form colored fine balls of uniform size, so that the material produces excellent effects when used as an additive for cosmetics, inks and plastics.
The material is expected to exhibit outstanding properties for use as a filler for high-performance chromatographs and gas chromatographs, magnetic tape and catalyst, and is also usable for spacers for liquid crystals.
2. Description of the Prior Art
Processes are already known for preparing inorganic particulate materials comprising porous fine balls with use of solutions, as disclosed, for example, in Examined Japanese Patent Publications SHO 54-6251 and SHO 57-55454.
These conventional processes consist essentially of mixing together an aqueous solution of water-soluble inorganic compound and an organic solvent to prepare a W/O emulsion, and subsequently mixing the emulsion with an aqueous solution capable of forming a water-insoluble precipitate when reacted with the water-soluble inorganic compound to produce porous fine balls of inorganic material.
Although the process described is an excellent process for producing an inorganic particulate material in the form of fine porous balls, the process has the tendency for the particles obtained to vary in size and encounters difficulty in preparing fine balls of substantially uniform size.
On the other hand, various processes are known for preparing emulsions. Recently developed is a process for producing an emulsion using a micro porous membrane as disclosed in Unexamined Japanese Patent Publication HEI 2-95433.
With this process, a liquid serving as the dispersed phase is forced into a liquid for providing the continuous phase through the micro porous membrane having pores of uniform diameter to obtain an emulsion.
We have conducted research on processes wherein the solution reaction is utilized for preparing porous inorganic particulate materials in order to overcome the above drawback.
During the research, we conceived the entirely novel idea that the emulsion producing technique using the micro porous membrane would be applicable to the preparation of such an inorganic particulate material. We have carried out further research based on this novel idea.